Potato peels are just fine to feed chickens, people, anyone. Almost all the vitamins in potatoes are found in the peel, the starch is in the flesh. Cooked or not, no problem.
HOWEVER, big CAVEAT here.... DO NOT feed chickens or people GREEN potato peels!!! Since potatoes are part of the nightshade family (like tomatoes, eggplant and deadly nightshade) if the peels get green from exposure to the sun they develop vastly increased levels of solanine which is toxic in very small quantities. Solanin is the same poison that is concentrated in deadly nightshade & tomato leaves. That's why you peel off the skin from greened potatoes, and it's better not to eat them at all!
Here's couple true stories... one good, one horrifiying.
1. During the Irish Potato Famine in the 1800s, the blight that destroyed the potato crop caused starvation and forced emigration to other countries. People were forced to eat their seed potatoes and any scrabbly potatoes that would grow. Fathers would give their children the flesh of the potatoes because it would fill their bellies, and only eat the skins. The skins contained the vitamins, so the fathers would be hungry but still be able to keep going.
2. A child died a few years ago from being poisoned by eating a tomato worm. It was the big, green ugly kind his mom had told him to pick off the tomato plants, and he'd forgotten to get them all, so she made him eat one as punishment. She didn't know those big tomato worms are full of poison from the tomato leaves and not even the birds eat them! That's why monarch butterfly caterpillars and big tomato worms look so much alike, so the birds avoid the non-lethal, tasty monarch caterpillars which appear about the same time as the tomato worms.